Vee-type internal combustion engines include at least two cylinders arranged in a vee-type configuration, each cylinder being rotated a transverse angle from a vertical engine centerline, in an amount equal to one half of a bank angle. For example, a conventional vee-type internal combustion engine may comprise a first bank which comprises a first plurality of in-line cylinders and a second bank which comprises a second plurality of in-line cylinders, each bank extending in the direction of a longitudinal axis which extends from one end of the internal combustion engine to the opposite end thereof, the cylinders in opposite banks forming a vee-shape configuration. In order to provide serviceability, a conventional cylinder liner having a flange is inserted into each cylinder. Each liner flange is square with a respective cylinder bore, and the engine block and cylinder head mate with opposite surfaces of each liner flange to hold it in place. One or more conventional gaskets are positioned between the engine block and cylinder head to provide the usual sealing.
In designing a vee-type internal combustion engine, it is desirable to provide a structure which satisfies performance objectives and yet is relatively compact. For example, providing a narrow vee-type engine by reducing cylinder spacing in the direction of the longitudinal axis of the engine, would increase engine compactness. However, in vee-type engines, various considerations tend to limit. increasing the degree of compactness obtainable. For example, designing a cylinder head for use in a narrow vee-type internal combustion engine presents various problems. The use of an individual head for each cylinder is not desirable since it would be necessary to provide more than one head configuration. Further, an individual head pattern would create poor head bolt location choices. In addition, exhaust passages on each alternating head would be very long thereby contributing adversely to heat exchange characteristics. In the alternative, a cylinder head could be provided adjacent each bank of the engine, but such a configuration would be contrary to the objective of engine compactness in that two exhaust manifolds would be required. Further, milling of separate firedecks for each bank is generally not possible because the cylinder bores overlap into respective opposite firedecks. For modern diesel engines having direct fuel injection, however, it is desirable to orient each cylinder head firedeck within the combustion chamber so that the firedeck is perpendicular to the centerline of the cylinder, and to have the fuel injection nozzle located and oriented along the cylinder centerline. A full length, one piece cylinder head is also not desirable since the use of cylinder liners will require liner counterbores in the head and engine block, and in such a configuration dimensional variations that adversely affect compression seal load distribution become a problem.
A further consideration is that in prior art vee-type internal combustion engines, the engine exhaust port passages are typically coupled to an exhaust manifold at one or more interface surfaces which are parallel to the horizontal axis of the engine block. This feature in combination with conventional valve and intake port patterns effects a configuration which defines lengthy exhaust port passages which provide less than optimum heat transfer characteristics. In addition, in considering assembling vee-type internal combustion engines, problems exist relating to the need to compensate for tolerances of, and equalization of load distribution between, paired cylinder liner flanges. Further, while it is desirable to shorten exhaust passages to improve heat exchange characteristics, it is also necessary for the air induction system to be uniform for each cylinder so that the same swirl characteristics exist for all cylinders. In considering possible cylinder head configurations which address all of the foregoing concerns, it is also necessary to provide an exhaust and intake port pattern which satisfactorily accommodates pushrod and other valve operating mechanisms, head hole locations and cooling water jacket design. All of these considerations present problems in the manufacture of a head for a narrow vee-type internal combination engine.